This invention relates to a connection structure for connecting, for example, a solenoid valve for hydraulic pressure control provided in a case of an automatic transmission of vehicles to a circuit body and a connection method thereof.
In automatic transmission of vehicles, a plurality of solenoid valves for hydraulic pressure control are distributed and disposed within an oil pan below a transmission case. A wire like wire harness is connected to each solenoid valve terminal so as to supply electric power.
In a conventional connection structure, a plurality of solenoid valves are mounted on an automatic transmission base. Each solenoid valve has a terminal. A conductor of the wire is connected to each terminal by soldering. Wires are bundled and connected to wire harness of vehicle body.
However, the above connection structure requires placing of wires to be connected to the solenoid valves and soldering between the conductor and terminal. For the reason, there are many steps for connection so that the procedure is complicated and takes a long time.
On the contrary, a connection structure enabling a snap connection not requiring soldering has been known. In this structure, a bus bar for forming a branch circuit is disposed in a gap formed between a base plate and a cover. A hole shaped female terminal is formed at a predetermined position of the bus bar. A pin terminal of the solenoid valve engages with the female terminal so that the bus bar is connected with the solenoid valve.
In the aforementioned structure, the snap connection is enabled so that working efficiency for connection is excellent. However, if a solenoid valve mounting accuracy is low, the contact between the female terminal and the pin terminal of the solenoid valve becomes unstable. This connection structure has a lower reliability as compared to the soldering method.
This is the same for other electronic parts than the solenoid valve. Therefore, such a structure in which connecting procedure is simple and a high reliability is ensured has been demanded.